Bag clamping system and method

Abstract

The invention discloses a bag clamping system and method, and belongs to the technical field of packaging equipment. In order to solve the problems that an existing bag clamping mechanism is insufficient in structural strength, inconvenient to disassemble, assemble and maintain and poor in clamping effect, the bag clamping system adopts a pair of clamping plates, and a U-shaped frame body of the clamping plates is inserted into a positioning groove of a bearing frame assembly through a top plate and a rectangular flange of a surrounding plate and is fixed through a bolt; the two-way cylinder driving mechanism is rigidly connected with the base plate through the supporting arm and the connecting plate to drive the clamping plate to clamp; the lower spring set and the upper spring set are arranged in a stepped mode, and clamping stability and sealing reliability are improved through multi-sensor control and stepped clamping. According to the mechanism, the maintenance efficiency is improved through the modular detachable design, the deformation resistance is enhanced through the stepped springs and the triangular supporting structure, packaging bags of different specifications can be stably clamped, and the mechanism is suitable for precise clamping of materials in a packaging machine and automatic packaging of high-fluidity materials.

Description

Technical Field

[0001] The present invention belongs to the technical field of packaging equipment, and particularly relates to a bag clamping system and method. Background Art

[0002] In the technical field of packaging equipment, the structural strength and clamping stability of the bag clamping mechanism directly affect the packaging efficiency and sealing quality. The existing bag clamping mechanism adopts a structural form of an integral welded frame directly connected to a cylinder. During long-term high-frequency clamping operations, cracks are likely to occur at the frame welds due to stress concentration, resulting in an increase in the cumulative offset of the clamping plate and affecting the clamping centering. The root cause of this problem lies in the lack of modular design of the traditional frame, and the cylinder driving force directly acts on the weak area of the clamping plate, exacerbating local fatigue failure. At the same time, the rigid connection method between the clamping plate and the driving mechanism requires the overall disassembly of the pneumatic components during maintenance. After reinstallation, the parallelism of the clamping plate needs to be repeatedly calibrated, which is complex and time-consuming.

[0003] Moreover, the layout of the homogeneous springs in the bag clamping mechanism is difficult to adapt to the working conditions where the material distribution at the bag mouth is uneven. When the filling amount in the bag fluctuates, the pressure distribution of the spring group is unbalanced. The upper region is prone to seal failure due to insufficient pressure, while the lower region is prone to material extrusion due to overloading. This phenomenon is mainly caused by the fact that the spring wire diameter and pre-tightening force are not designed differently according to the regional load characteristics, resulting in the inability of the clamping force gradient to match the actual material distribution law. In addition, the conventional bag clamping system lacks a dynamic feedback mechanism during the clamping process and cannot adjust the clamping parameters in real time according to the thickness of the bag mouth or the fluidity of the material. The thin-walled bag mouth is prone to deformation due to too fast speed or too large pressure, while the thick-walled bag mouth has insufficient sealing due to the compressive hysteresis effect.

[0004] In terms of exhaust control, when the bag clamping mechanism adopts a fixed pressure holding time and a static threshold, it is difficult to adapt to packaging bag materials with different air permeabilities. When the gas in the bag is not exhausted completely, the residual gas is likely to cause the bag mouth to bulge or be poorly welded, while overpressure holding increases the energy consumption and the risk of damage to the packaging bag. The core of this problem lies in the lack of real-time monitoring and adaptive regulation capabilities for the exhaust efficiency. In addition, when the position of the bag mouth shifts or the material distribution changes suddenly, the existing system cannot quickly correct the clamping trajectory and pressure distribution, resulting in unilateral seal failure or clamping misalignment.

[0005] The solutions to the above problems face the following difficulties: First, how to achieve modular design of the clamping components within a limited space, which not only ensures the structural strength but also facilitates quick disassembly, installation, and maintenance; second, how to construct a dynamic clamping force distribution mechanism to make the spring stiffness and pressure gradient accurately adapt to the change of material distribution; third, how to synchronously achieve multi-parameter closed-loop control of thickness detection, exhaust monitoring, and pressure adjustment during high-speed clamping to avoid system response lag or parameter coupling interference. These technical bottlenecks have long restricted the high-speed and high-precision development of the bag clamping system. Summary of the Invention

[0006] An object of the present invention is to provide a bag clamping system, which solves the problems that the bag clamping mechanism adopts an integral welded frame and a direct connection structure with a cylinder. Long-term high-frequency clamping is likely to cause weld cracks due to stress concentration, and the cumulative offset of the clamping plates affects the clamping accuracy; the layout of the homogeneous springs is difficult to adapt to the working conditions of uneven material distribution, and there are coexisting problems of seal failure and material extrusion; maintenance requires the overall disassembly of pneumatic components, and the calibration complexity is high.

[0007] In order to achieve these objects and other advantages of the present invention, a bag clamping system provided by the present invention includes: A pair of clamping plates, symmetrically arranged on both sides of the packaging bag conveying path. Each clamping plate includes a U-shaped frame body with an open bottom end. The frame body is composed of a top plate and side plates extending downward on both sides. Rectangular flanges are provided on the outer sides of the top plate and the side plates; a supporting frame assembly, including a horizontal substrate, side plates vertically welded to both sides of the substrate, and inclined reinforcing plates connecting the side plates and the substrate. The included angles between the inclined reinforcing plates and the substrate and the side plates are 30 degrees to 60 degrees. Rectangular positioning grooves matching the flanges of the clamping plates are provided on the inner sides of the side plates. After the flanges are inserted into the positioning grooves, they are fixed by bolts; a double-acting cylinder driving mechanism, whose cylinder body is fixed to the frame. The telescopic end of the double-acting cylinder driving mechanism is rigidly connected to the substrate of the supporting frame assembly through a support arm and a connecting plate; a spring assembly, including a lower spring group and an upper spring group installed on the inner sides of the side plates of the clamping plates. The lower spring group is composed of helical compression springs with a wire diameter of 1.2 mm to 1.8 mm, and the distance between adjacent springs is 4 mm to 6 mm. The upper spring group is composed of helical compression springs with a wire diameter of 0.8 mm to 1.2 mm, and the distance between adjacent springs is 8 mm to 10 mm. The free height of the lower spring group is 3 / 8 of the height of the side plate, and the free height of the upper spring group is 5 / 8 of the height of the side plate; a sinking groove is provided on the top of the horizontal substrate of the supporting frame assembly, and the length of the sinking groove is the same as the length of the flange of the top plate of the clamping plate. The bottom surface of the sinking groove contacts the lower surface of the flange of the top plate; an inclined reinforcing rod is welded between the connecting plate and the side plate of the supporting frame assembly. One end of the inclined reinforcing rod is welded to the lower side surface of the connecting plate, and the other end is welded to the lower part of the side plate of the supporting frame assembly.

[0008] During the clamping process, the upper part of the bag mouth, which is the material-free area, lacks support and is prone to wrinkles caused by sagging or offset. The conventional bag clamping system does not have a pre-fixing mechanism for the material-free area, resulting in pressure imbalance during the sealing stage. Preferably, several elastic pressing pieces are arranged on the upper part of the top plate of the clamping plate of the present invention. The elastic pressing pieces extend obliquely inward and upward towards the clamping plate, and the ends are bent into arc-shaped contact surfaces. The elastic pressing pieces are arranged along the length direction of the top plate, and the positions of the elastic pressing pieces on the left and right clamping plates correspond to each other, forming a clamping limit for the packaging bag. During the closing process of the clamping plate, the lower spring group first contacts and compresses the material area of the bag mouth. When the clamping plate continues to move, the arc-shaped contact surface of the elastic pressing piece contacts the upper part of the bag mouth, providing a pre-pressure through elastic deformation, and simultaneously lifting the bag mouth to eliminate sagging deformation. Finally, the upper spring group presses the upper part of the bag mouth, and the sealing is completed through the spring compression force. The gap between adjacent elastic pressing pieces forms an exhaust channel.

[0009] The traditional bag clamping system relies on fixed cylinder parameters and cannot real-time sense the deviation of the clamping force distribution (such as overpressure in the lower part or underpressure in the upper part), resulting in out-of-control clamping force (sealing failure or material leakage). Preferably, pressure sensors are arranged on the inner side of the enclosing plate of the clamping plate of the present invention. The pressure sensors real-time monitor the clamping force data of the lower spring group and the upper spring group during the clamping process and feed the data back to the PLC controller. The PLC controller has a preset clamping force distribution curve, which is set according to the material distribution characteristics and sealing requirements of the packaging bag. During the closing process of the clamping plate, the PLC controller compares the deviation between the real-time clamping force data and the preset curve, and dynamically compensates for the local imbalance of the clamping force by adjusting the output pressure of the bidirectional cylinder driving mechanism. The clamping force distribution curve includes the pre-pressing stage of the lower spring group and the auxiliary sealing stage of the upper spring group, and the pressure gradients of the two stages are smoothly transitioned through the proportional-integral algorithm of the PLC controller.

[0010] The clamping stage switching depends on a single sensor (such as a pressure or time threshold), which is prone to inaccurate loading timing due to signal interference or working condition fluctuations, and sudden pressure changes can cause bag mouth deformation or sealing failure. Preferably, the preloading stage and the auxiliary sealing stage of the clamping force distribution curve of the present invention are smoothly transitioned through the following steps: at the initial stage of the clamping plate closing, the PLC controller controls the bidirectional cylinder driving mechanism to increase the output pressure at the first pressure slope, so that the lower spring group is compressed to a preset preloading threshold, and the preloading threshold corresponds to the initial sealing pressure of the packaging bag material area; when the pressure sensor detects that the pressure of the lower spring group reaches the preloading threshold, the PLC controller switches to the second pressure slope and increases the output pressure at a rate lower than the first pressure slope, and synchronously starts the auxiliary sealing action of the upper spring group; the proportional-integral algorithm dynamically adjusts the second pressure slope according to the real-time pressure difference between the lower spring group and the upper spring group to ensure that the pressure gradient change rate of the two stages does not exceed the preset fluctuation tolerance; at the end of the clamping action, the PLC controller controls the cylinder output pressure to enter the pressure holding stage, maintaining the preset upper and lower pressure ratios in the clamping force distribution curve until the sealing detection unit completes the sealing verification.

[0011] When using fixed valve control parameters during stage switching, it is impossible to adapt to the attenuation of spring performance or the dynamic distribution of materials, resulting in sudden pressure changes (sealing failure or bag mouth wrinkles). Preferably, displacement sensors are symmetrically arranged between the clamping plates of the present invention, and the detection ends of the displacement sensors point in the direction of the clamping plate closing; at the initial stage of the clamping plate closing, the displacement sensors continuously detect the relative moving distance between the two clamping plates and transmit the detection data to the PLC controller through a high-speed counter; when the moving distance reaches 3 / 8 of the height of the clamping plate surrounding plate, the PLC controller generates a trigger signal to control the bidirectional cylinder driving mechanism to switch to the auxiliary sealing stage and start the loading action of the upper spring group; the trigger signal synchronously adjusts the opening of the cylinder control valve to make the pressure loading rate of the upper spring group match the pressure gradient of the preloading stage of the lower spring group.

[0012] Traditional clamping bag systems rely on fixed pressure holding times and cannot be dynamically adjusted according to the actual exhaust effect, which easily leads to gas residue (poor sealing) or over-compression (bag mouth damage). Preferably, after the trigger signal of the present invention is generated, the PLC controller performs the following coordinated control actions: obtaining the real-time moving distance data of the displacement sensor through a high-speed counter and calculating the pressure gradient change rate during the preloading stage of the lower spring group; dynamically setting the opening adjustment curve of the cylinder control valve according to the pressure gradient change rate, and the adjustment curve is a linearly increasing function, and its slope is inversely proportional to the pressure gradient change rate of the lower spring group; the cylinder control valve is a proportional valve, and its opening is adjusted synchronously according to the adjustment curve to make the pressure loading rate of the upper spring group match the pressure gradient during the preloading stage of the lower spring group; during the auxiliary sealing stage, the PLC controller monitors the pressure rise curve of the upper spring group in real time through a pressure sensor. If it detects that the pressure fluctuation amplitude exceeds the preset threshold, the opening adjustment curve of the cylinder control valve is corrected through a proportional-integral algorithm; the corrected opening adjustment curve suppresses the pressure oscillation by superimposing a reverse compensation amount.

[0013] Traditional exhaust control uses empirically set fixed thresholds and cannot adapt to differences in packaging bag materials or operating condition fluctuations, resulting in a high risk of misjudgment. Preferably, gas flow sensors are symmetrically installed on the outer side of the top plate of the clamping plate of the present invention, and the detection ends of the gas flow sensors face the exhaust channels of the packaging bag; during the clamping process, the gas flow sensors monitor the gas discharge flow rate inside the bag in real time and feed the flow data back to the PLC controller; when it detects that the gas flow rate per unit time drops to the preset threshold, the PLC controller performs the following actions: increasing the output pressure of the double-acting cylinder drive mechanism on the lower spring group through a proportional valve, and the increase range is 10% to 20% of the current pressure; synchronously extending the duration of the pressure holding stage of the clamping action, and the extension amount is 1.2 to 1.5 times the initially set time; the gas flow threshold is dynamically set through the built-in algorithm of the PLC according to the air permeability coefficient and material density of the packaging bag; during the extended period of the pressure holding stage, the PLC controller continuously monitors the change in gas flow rate. If the flow rate rises above the threshold, a clamping action termination instruction is triggered and the sealing performance detection process is entered.

[0014] The clamping bag system adopts fixed cylinder speed and pressure parameters and cannot adapt to the dynamic change of the bag mouth thickness, resulting in the thin bag being clamped and broken or the thick bag being insufficiently clamped. Preferably, the dynamic setting of the gas flow threshold of the present invention is achieved through the following steps: A mapping relationship database of the air permeability coefficient of the packaging bag and the material density is pre-stored in the PLC controller. The air permeability coefficient is measured by experiments on the air permeability rate of packaging bags of different materials and classified and stored; when the packaging bag enters the clamping station, the material type and material density data of the current batch of packaging bags are input through the human-machine interface or the QR code scanner, and the PLC controller calls the mapping relationship database to match the corresponding air permeability coefficient; based on the air permeability coefficient and the material density, the initial value of the gas flow threshold is calculated by the linear interpolation algorithm. The initial value increases with the increase of the air permeability coefficient and decreases with the increase of the material density; during the clamping process, the PLC controller dynamically corrects the threshold according to the real-time gas flow data, and the correction amount is ±5% to ±10% of the initial value, and the correction frequency is once every 10 seconds to 30 seconds; during the extended period of the pressure holding stage, if the gas flow rises to 105% to 110% of the corrected threshold, it is determined that the gas in the bag has been exhausted, and the PLC controller immediately terminates the clamping action and starts the sealing detection process; if the flow is still lower than the threshold after being detected to rise continuously three times, it is determined that the packaging bag is damaged or the clamping fails, and an alarm signal is triggered and the clamping plate is forced to retract to the initial position.

[0015] The thick-walled bag mouth has strong compression resilience, and the anti-pressure hysteresis effect results in low clamping efficiency; the high-speed clamping of thin bags is likely to cause mechanical shock. Preferably, laser thickness gauges are symmetrically installed on the outer side of the top plate of the clamping plate of the present invention. The optical path of the emitting end and the receiving end of the laser thickness gauge is perpendicular to the clamping surface for real-time detection of the thickness of the packaging bag mouth; the detection data of the laser thickness gauge is transmitted to the PLC controller through a high-speed data bus, and the PLC controller dynamically generates a cylinder speed regulation instruction according to the bag mouth thickness; when the bag mouth thickness is less than the preset nominal value, the PLC controller reduces the closing speed of the double-acting cylinder drive mechanism to 70% to 80% of the nominal speed to avoid clamping deformation caused by too fast speed of the thin-walled bag mouth; when the bag mouth thickness is greater than the preset nominal value, the PLC controller increases the cylinder closing speed to 120% to 150% of the nominal speed to compensate for the anti-pressure hysteresis effect of the thick-walled bag mouth; the cylinder speed regulation instruction is linearly adjusted through the opening of the proportional valve, and the speed change rate is limited to 5% to 10% per second to prevent the clamping plate from vibrating caused by sudden acceleration; the preset nominal value is matched by the look-up table method of the PLC controller according to the packaging bag material type, and the laser thickness measurement data is updated every 2 seconds to 5 seconds during the clamping process.

[0016] Aiming at the technical problem that the traditional bag clamping method lacks a multi-parameter collaborative control logic, and it is difficult to balance the clamping force, exhaust efficiency and thickness adaptability, resulting in a low packaging qualification rate. A bag clamping method for a bag clamping system provided by the present invention includes: A pair of clamping plates are symmetrically arranged on both sides of the packaging bag conveying path. The U-shaped frame of each clamping plate is inserted into the rectangular positioning groove of the supporting frame assembly through the rectangular flange of the top plate and the surrounding plate, and fixed by bolts. The supporting frame assembly is formed by welding a horizontal base plate, a vertical side plate and an inclined reinforcing plate to form a triangular support structure. The included angle between the inclined reinforcing plate and the base plate and the side plate is 30 degrees to 60 degrees; the supporting arm and the connecting plate are driven by a double-acting cylinder driving mechanism, so that the supporting frame assembly drives the clamping plates to move towards the center to form a clamping; during the closing process of the clamping plates, the lower spring group and the upper spring group installed inside the surrounding plate of the clamping plates are used to apply clamping force in stages: the lower spring group is composed of helical compression springs with a wire diameter of 1.2 mm to 1.8 mm, the distance between adjacent springs is 4 mm to 6 mm, and the free height is 3 / 8 of the height of the surrounding plate. At the initial stage of closing, the output pressure of the cylinder is increased at the first pressure slope, so that the lower spring group is compressed to a preset preloading threshold; when the pressure sensor detects that the pressure of the lower spring group reaches the preloading threshold, it switches to the second pressure slope, and the output pressure is increased at a rate lower than the first pressure slope. At the same time, the auxiliary sealing action of the upper spring group is started. The upper spring group is composed of helical compression springs with a wire diameter of 0.8 mm to 1.2 mm, the distance between adjacent springs is 8 mm to 10 mm, and the free height is 5 / 8 of the height of the surrounding plate; the relative moving distance between the two clamping plates is detected in real time by a displacement sensor. When the moving distance reaches 3 / 8 of the height of the surrounding plate, a signal is triggered to control the cylinder to switch to the auxiliary sealing stage, and the second pressure slope is dynamically adjusted by a proportional-integral algorithm to ensure that the pressure gradient change rate of the two stages does not exceed the preset fluctuation tolerance; at the end of clamping, enter the pressure holding stage and maintain the preset upper and lower pressure ratios. At the same time, the gas discharge flow rate in the bag is monitored by a gas flow sensor: if the flow rate per unit time drops to the dynamically set threshold, the pressure of the lower spring group is increased by 10% to 20%, and the pressure holding time is extended to 1.2 times to 1.5 times of the initial setting; if the flow rate rebounds and exceeds the threshold, the clamping is terminated and the sealing performance detection is started; the thickness of the bag mouth is detected in real time by a laser thickness gauge, and the closing speed and preloading pressure of the cylinder are dynamically adjusted: when the thickness is less than the nominal value, the cylinder speed is reduced to 70% to 80% of the nominal value, and the preloading pressure is increased to 120% to 130%; when the thickness is greater than the nominal value, the cylinder speed is increased to 120% to 150% of the nominal value, and the preloading pressure is reduced to 80% to 90%; the control command is linearly adjusted by the opening of the proportional valve, the speed change rate is limited to 5% to 10% per second, and the thickness measurement data is updated every 2 seconds to 5 seconds; after the sealing performance detection is completed, if there are still defects after 3 consecutive calibrations, it is determined that the component is abnormal and a maintenance reminder is triggered.

[0017] The present invention has at least the following beneficial effects: 1. The present invention simplifies the maintenance process through the detachable flange-positioning groove structure and the separate design of the clamping plate and the supporting frame assembly. When replacing the clamping plate, there is no need to disassemble the cylinder assembly as a whole; the triangular support structure (inclined reinforcing plate + oblique reinforcing rod) significantly improves the bending stiffness of the supporting frame and disperses the stress concentration area; the stepped spring group (high stiffness at the bottom and low stiffness at the top) adapts to the difference in material distribution at the bag mouth. The lower spring group gives priority to compacting the material area, and the upper spring group flexibly seals the material-free area to reduce gas residue and material extrusion. The sink and flange cooperate to limit the lateral deviation of the clamping plate and ensure the linearity of the clamping action.

[0018] 2. The inclined extension and arc-shaped end design of the elastic pressing sheet of the present invention form a tangential friction force when it contacts the upper part of the bag opening in the later stage of clamping, thereby eliminating the sagging wrinkles in the material-free area; the exhaust channel formed by the pressing sheet interval allows the gas to be discharged efficiently to avoid bulging of the bag opening; the left and right pressing sheet alignment layout ensures that the bag opening is centered to reduce deviation.

[0019] 3. The present invention uses a pressure sensor to monitor the distribution of the clamping force in the upper and lower parts in real time. The PLC dynamically compensates for local imbalances (such as pressurization at the lower part and decompression at the upper part) through a preset curve, so that the clamping force gradient accurately matches the density change of the bag mouth material; the proportional integral algorithm smoothly transitions the two-stage pressure gradient to eliminate the bag mouth deformation caused by step loading. The closed-loop feedback mechanism limits the fluctuation amplitude of the clamping force and improves the sealing consistency.

[0020] 4. The staged pressure slope control (high first slope, low second slope) of the present invention realizes the progressive loading of the clamping force: the lower spring group quickly pre-compresses the material area, and the upper spring group slowly supplements the sealing pressure. The second slope is dynamically adjusted by the pressure difference to ensure that the pressure change rate of the two stages does not exceed the preset tolerance, avoiding sudden pressure changes that cause sealing failure or bag mouth wrinkles.

[0021] 5. The displacement sensor of the present invention accurately determines the position of the clamping plate, and the trigger signal synchronously adjusts the cylinder valve opening, so that the loading rate of the upper spring group matches the lower preload gradient.

[0022] 6. The present invention dynamically generates a proportional valve opening adjustment curve (the slope is inversely proportional to the gradient) based on the pressure gradient change rate in the lower pre-pressing stage, so that the upper loading rate can adapt to the lower mechanical state; when the pressure fluctuation exceeds the limit, the proportional-integral algorithm superimposes the reverse compensation amount to suppress the oscillation caused by the difference in spring stiffness or material shaking, and reduce the pressure fluctuation amplitude.

[0023] 7. The gas flow sensor of the present invention monitors the exhaust efficiency in real time. When the flow rate is lower than the dynamic threshold, the boost and extended maintenance work together to ensure that the gas is exhausted while avoiding excessive compression; the flow rate rises and triggers immediate termination, reducing the invalid pressure holding time and energy consumption. The dynamic threshold is adapted to different permeable materials to reduce misjudgment.

[0024] 8. The present invention dynamically sets the initial flow threshold through the mapping database of the air permeability coefficient and the material density and the linear interpolation algorithm, eliminating the manual experience error; the real-time correction mechanism responds to the changes in environmental temperature and humidity, improving the adaptability of the threshold. The continuous low-flow alarm quickly locates the clamping failure or bag breakage, improving the troubleshooting efficiency.

[0025] 9. The real-time data of the laser thickness gauge of the present invention drives the regulation of the cylinder speed and pressure: reducing the speed and increasing the pressure for thin bags to prevent deformation, and increasing the speed and reducing the pressure for thick bags to compensate for hysteresis. The limitation of the speed change rate suppresses mechanical shock and improves the clamping stability; the thickness measurement data is updated every 2 - 5 seconds to adapt to the thickness fluctuation of the bag mouth.

[0026] 10. The collaborative control of multiple sensors (displacement, pressure, flow, thickness measurement) of the present invention realizes the adaptive matching of the clamping force, exhaust efficiency and thickness parameters; the phased clamping logic (pre-pressing - auxiliary sealing - pressure maintaining) optimizes the resource allocation and improves the packaging efficiency; the correlation analysis of abnormal data (such as continuous calibration failure) accurately locates the fault source and reduces the maintenance cost.

[0027] Other advantages, objectives and features of the present invention will be partially reflected by the following description, and partially will also be understood by those skilled in the art through the research and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a schematic structural diagram of the bag clamping system and method of the present invention; Figure 2 is a schematic structural diagram of the cooperation between the supporting frame assembly and the clamping plate of the present invention; Figure 3 is a schematic structural diagram of the supporting frame assembly of the present invention; Figure 4 is a flow framework diagram of the bag clamping method of the present invention.

[0029] Among them, the frame 1, the bidirectional cylinder driving mechanism 2, the support arm 3, the connecting plate 4, the supporting frame assembly 5, the clamping plate 6, the packaging bag 7, the conveying path 8, the displacement sensor 9, the air flow sensor 10, the thickness gauge 11, the diagonal strengthening rod 401, the base plate 501, the side plate 502, the inclined strengthening plate 503, the positioning groove 504, the sunk groove 505, the top plate 602, the surrounding plate 603, the top plate flange 604, the surrounding plate flange 605, the elastic pressing piece 606, the lower spring group 6011, the upper spring group 6012. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] The following further describes the present invention in detail with reference to the embodiments, so that those skilled in the art can implement it according to the description in the specification.

[0031] As shown in FIGS. 1 - 3, an example of a bag clamping system of the present invention includes: A pair of symmetrically arranged clamping plates 6, a supporting frame assembly 5, and a double-acting cylinder driving mechanism 2. The clamping plate 6 is composed of a top plate 602 and surrounding plates 603 extending downward on both sides to form a U-shaped frame. The top plate and the surrounding plates have rectangular flanges, including a top plate flange 604 and a surrounding plate flange 605. The flange thickness is 6 - 10 mm, and the width is 15 - 25 mm. The material can be selected as steel plate, and the surface is treated with galvanization to improve corrosion resistance.

[0032] The supporting frame assembly 5 is welded by a horizontal base plate 501, vertical side plates 502, and inclined reinforcing plates 503. The included angle between the inclined reinforcing plate 503 and the base plate 501 and the side plate 502 is 30 - 60 degrees. The thickness of the inclined reinforcing plate 503 is 5 - 7 mm, and the material can be the same stainless steel as the base plate 501. The depth of the rectangular positioning groove 504 provided on the inner side of the side plate 502 is 5 - 8 mm, and the width is 0.5 - 1 mm wider than the flange. The cylinder body of the double-acting cylinder driving mechanism 2 is fixed to the cross beam of the frame 1 by bolts, and its telescopic end is connected to the support arm 3 through a flange. The support arm 3 and the connecting plate 4 are rigidly fixed by M12 bolts, and the connecting plate 4 and the base plate 501 of the supporting frame assembly 5 are locked by countersunk head bolts.

[0033] After the rectangular flange of the clamping plate 6 is inserted into the positioning groove 504 of the supporting frame assembly 5, it is fixed by four M10 hexagon head bolts. The bolt pre-tightening torque is 15 - 25 N·m. The bolt holes are symmetrically distributed on both sides of the positioning groove 504, and the hole spacing is 20 - 30 mm. The double-acting cylinder driving mechanism 2 can select a standard double-rod cylinder, with a stroke range of 100 - 200 mm and an output thrust of 500 - 800 N. A muffler is preferably installed at the air inlet of the cylinder to reduce noise.

[0034] On the top of the horizontal substrate 501 of the supporting frame assembly 5, a sunk groove 505 is provided. The length of the sunk groove 505 is the same as that of the top plate flange 604 of the clamping plate 6. The width of the sunk groove 505 can be 0.3 - 0.8 mm wider than the flange. For example, when the width of the flange is 20 mm, the width of the sunk groove 505 is designed to be 20.3 - 20.8 mm, and the depth of the sunk groove 505 is 6 - 11 mm. The bottom surface of the sunk groove 505 can be processed by face milling. The assembly gap between the side wall of the sunk groove 505 and the side surface of the flange can be controlled within 0.2 - 0.5 mm. The top of the side wall is machined with a 45-degree chamfer, the chamfer width is 1 - 2 mm, and the chamfer depth is 0.5 - 1 mm. During assembly, the axis of the sunk groove 505 coincides with the longitudinal center line of the horizontal substrate 501, and the bottom surface of the sunk groove 505 contacts the lower surface of the top plate flange 604 of the clamping plate 6, and the contact area accounts for more than 90% of the lower surface of the flange. The bolt mounting holes on both sides of the sunk groove 505 are symmetrically distributed on the edge of the substrate 501, with a hole diameter of 10.5 mm, matching M10 bolts. The pre-tightening torque of the bolts is 15 - 25 N·m, and the bolt head is designed with a countersunk head to avoid interfering with the movement of the clamping plate 6. During the clamping process, the sunk groove 505 bears the vertical load of the top plate of the clamping plate 6 through the bottom surface, and at the same time, the side walls limit the lateral displacement of the flange, improving the transmission efficiency of the cylinder driving force.

[0035] An inclined reinforcing bar 401 is welded between the connecting plate 4 and the side plate 502 of the supporting frame assembly 5. One end of the inclined reinforcing bar 401 is welded to the lower side of the connecting plate 4, and the other end is welded to the lower part of the side plate 502 of the supporting frame assembly 5. The thickness of the inclined reinforcing bar 401 is 6 - 8 mm, such as 7 mm. Steel plates can be selected and the surface is treated with rust prevention to improve durability. The angle between the axis of the inclined reinforcing bar 401 and the side surface of the connecting plate 4 is 45 - 60 degrees, such as 50 degrees or 55 degrees. The length of the bar body is 1.1 - 1.3 times the distance between the two welding points. For example, when the distance is 200 mm, the bar length is designed to be 220 - 260 mm. The welding method uses double-sided continuous fillet welds, and the leg height of the weld is 4 - 6 mm. The surface of the weld is polished to avoid stress concentration. The design of the inclined reinforcing bar 401 in this embodiment can improve the lateral support.

[0036] The splint 6 is provided with a spring assembly composed of multiple parallel springs. The multiple parallel springs are horizontally installed between the two enclosing plates 603 to form an elastic contact surface. In the illustration, both ends of the springs are respectively hooked and connected to the enclosing plates 603 on both sides to keep horizontal. The wire diameter of the parallel springs is 0.8 - 1.8 mm, such as 1.0 mm or 1.2 mm, etc. The material can be selected from 65Mn spring steel or 304 stainless steel, and the surface is treated by phosphating or passivation to improve wear resistance. The springs protrude outward from the inner surface of the enclosing plate 603 by 2 - 4 mm in the natural state, such as 3 mm, and the distance between adjacent springs is 4 - 8 mm, such as 6 mm. During the clamping operation, the elastic contact surface of the spring assembly can adapt to the working conditions with fluctuating thickness of the bag mouth, and improve the uniformity of the clamping force distribution.

[0037] The spring assembly is arranged in stages and includes a lower spring group 6011 and an upper spring group 6012 installed inside the enclosing plate 603 of the frame. The lower spring group 6011 is composed of helical compression springs with a wire diameter of 1.2 - 1.8 mm, such as 1.5 mm, the distance between adjacent springs is 4 - 6 mm, such as 5 mm, and the stiffness coefficient of the lower spring group is 15 - 25 N / mm; the upper spring group 6012 is composed of helical compression springs with a wire diameter of 0.8 - 1.2 mm, such as 1.0 mm, the distance between adjacent springs is 8 - 10 mm, such as 9 mm, and the stiffness coefficient of the upper spring group is 5 - 10 N / mm. The free height of the lower spring group 6011 is 3 / 8 of the height of the enclosing plate 603. For example, when the height of the enclosing plate 603 is 80 mm, the free height is 30 mm. This production line is set to this ratio, and others should be adjusted according to the actual situation of the production line. The lower spring group corresponds to the bag mouth material area; the free height of the upper spring group 6012 is 5 / 8 of the height of the enclosing plate 603, such as 50 mm. This production line is set to this ratio, and others should be adjusted according to the actual situation of the production line. The upper spring mainly covers the upper part of the bag mouth without materials. During the closing process of the splint 6, the lower spring group 6011 contacts the bag mouth material area first due to its lower free height. After applying a pre-pressure of about 15 - 25 N, the upper spring group 6012 starts to compress and applies an auxiliary pressure of about 5 - 10 N. Staged loading can reduce the gas residue in the packaging bag mouth and reduce the extrusion of materials.

[0038] One implementation process of this embodiment is as follows: The packaging bag 7 is moved between the two clamping plates 6 through the conveying platform. After the air cylinder is started, the telescopic end pushes the supporting frame assembly 5 to move towards the center, and the moving clamping plates 6 are clamped. When the clamping plates 6 are closed, the lower spring group 6011 (wire diameter 1.5 mm) first contacts the material area at the bag mouth due to its lower free height, and applies a pre-pressure of about 20 N within 10 ms; the upper spring group 6012 (wire diameter 1.0 mm) starts to compress with a delay of 15 ms and applies an auxiliary pressure of about 8 N. The gas in the bag is discharged through the spring gap. The dense area of the lower spring (spacing 5 mm) forms the main sealing surface, and the sparse area of the upper spring (spacing 9 mm) assists in sealing the section of the bag mouth without material.

[0039] Further, in another embodiment, several elastic pressing pieces 606 can be arranged on the upper part of the top plate 602 of the clamping plate 6. The elastic pressing pieces 606 extend inward and upward obliquely towards the clamping plate 6, and the inclination angle can be selected from 30 degrees, 35 degrees or 40 degrees. The end is bent into an arc-shaped contact surface, and the arc radius can be selected from 5 mm, 6 mm or 8 mm. The elastic pressing pieces 606 are arranged along the length direction of the top plate 602, and the spacing between adjacent pressing pieces can be set according to actual needs, such as 20 mm. In the illustration, four elastic pressing pieces 606 can be arranged on one clamping plate 6. The elastic pressing pieces 606 at the left and right ends are necessary, and the middle elastic pressing pieces can be set or not. The positions of the pressing pieces on the left and right clamping plates 6 correspond, and the deviation is controlled within ±1 mm to facilitate clamping. The roots of the elastic pressing pieces 606 are fixed to the reserved hole positions of the top plate 602 through countersunk head bolts.

[0040] The base material of the elastic pressing piece 606 can be selected from 60Si2Mn spring steel sheets or plastic sheets, and the thickness can be selected from 0.8 mm, 1.0 mm or 1.2 mm. The surface is coated with a food-grade silica gel layer with a Shore hardness of 50A to 60A, and the thickness of the silica gel layer can be selected from 1.0 mm, 1.2 mm or 1.5 mm. During installation, the arc-shaped contact surface at the end of the pressing piece 606 is 5 mm to 8 mm higher than the top of the upper spring group 6012 in the free state to ensure that the pressing piece contacts the bag mouth first.

[0041] During the closing process of the clamping plate 6, the lower spring group 6011 compresses the material area at the bag mouth under the action of a spring with a wire diameter of 1.5 mm at a pressure slope of 0.5 MPa / s. When the displacement sensor 9 detects that the clamping plate 6 moves to 2 / 3 of the height of the surrounding plate 603 (for example, when the height of the surrounding plate 603 is 80 mm, the trigger position is 53 mm), the PLC controller generates a trigger signal and switches to the auxiliary sealing stage. At this time, the elastic pressing piece 606 contacts the non-material area at the upper part of the bag mouth, provides a pre-pressure of 3 N, 4 N or 5 N through elastic deformation, and lifts the bag mouth by 2 mm, 3 mm or 4 mm to eliminate the sag deformation. Finally, the upper spring group 6012 presses the upper part of the bag mouth at a pressure slope of 0.3 MPa / s, and the spring is compressed to 60% to 70% of its free height.

[0042] The cylinder output pressure of the cylinder drive mechanism 2 in the auxiliary sealing stage can be set to 0.4 MPa, 0.5 MPa or 0.6 MPa, and the pressure adjustment response time ≤ 50 ms. The detection accuracy of the displacement sensor 9 (such as an LVDT linear sensor) is ±0.1 mm, and the signal is transmitted to the PLC through a high-speed counter at a cycle of 10 ms.

[0043] The gap between adjacent elastic pressing pieces 606 forms an exhaust channel. In the illustration, at least one elastic pressing piece 606 is provided on each side of the bag mouth of the packaging bag 7, and multiple ones can be provided in the middle (set according to the actual bag mouth width specification of the packaging bag 7). The gas in the bag is discharged through the gap of the pressing piece. The surface friction coefficient of the silicone layer of the pressing piece 606 is 0.3 to 0.5, and the lateral offset of the bag mouth during the clamping process ≤ 1 mm.

[0044] The elastic deformation amount of the pressing piece 606 is limited to 4 mm, 5 mm or 6 mm, and the return spring (wire diameter 0.8 mm to 1.0 mm) provides a return force of 2 N to 3 N to ensure that the pressing piece automatically resets after the clamping ends. The action timing delay between the pressing piece and the upper spring group 6012 can be set to 50 ms, 80 ms or 100 ms to avoid mechanical interference.

[0045] The phased intervention of the elastic pressing piece 606 in this embodiment reduces the wrinkles at the upper part of the bag mouth; the pre-pressure of the pressing piece and the main clamping force of the spring act together to improve the sealing uniformity; the exhaust channel design reduces the gas residue rate, and the sealing qualification rate is increased to more than 98%; the silicone layer protection avoids scratching the bag mouth, and the breakage rate of the thin-walled bag is reduced to less than 0.5%.

[0046] Further, in another embodiment, a micro pressure sensor 607 can be installed inside the shroud 603 of the clamping plate 6. The pressure sensor 607 is arranged in the telescopic area of the lower spring group 6011 and the upper spring group 6012. Each spring group corresponds to 2 - 4 sensors, and the sensor spacing can be selected as 50mm, 60mm or 70mm. The measuring range of the pressure sensor 607 can be selected as 0 - 50N or 0 - 100N, the accuracy is ±0.5% FS, and the sampling frequency can be set as 100Hz, 150Hz or 200Hz. The sensor signal is transmitted to the PLC controller through a shielded cable, and the cable length does not exceed 5m.

[0047] The pressure sensor 607 can be a piezoresistive or piezoelectric sensor, and the housing material is 316 stainless steel with an IP67 protection level. During installation, the surface of the pressure sensor 607 is flush with the spring end faces of the spring groups (6011, 6012) and is fixed by epoxy resin glue with a glue layer thickness ≤0.2mm. The power supply voltage of the pressure sensor 607 is 5VDC or 10VDC, and the signal output is 4 - 20mA or 0 - 10V.

[0048] The clamping force distribution curve preset in the PLC controller is set according to the material distribution characteristics of the packaging bag 7. For example, the target pressure in the material concentration area (lower part) can be set as 30N, 40N or 50N, and the target pressure in the no - material area (upper part) can be set as 10N, 15N or 20N. The preset curve includes a pre - pressing stage (0 - 2 seconds) and an auxiliary sealing stage (2 - 5 seconds), and the pressure gradient slope can be selected as 10N / s, 15N / s or 20N / s. The deviation threshold between the real - time clamping force data and the preset curve is set as ±5N, ±8N or ±10N, and a dynamic compensation instruction is triggered when the threshold is exceeded.

[0049] The dynamic compensation is achieved by adjusting the output pressure of the cylinder through a proportional valve, and the pressure adjustment range can be selected as 5%, 10% or 15% of the current value. For example, when the pressure of the lower spring group 6011 is 10N lower than the preset value, the output pressure of the cylinder is increased by 10%; when the pressure of the upper spring group 6012 is 5N higher than the preset value, the output pressure of the cylinder is decreased by 8%. The PLC controller updates the control parameters every 50ms, and the response delay ≤20ms.

[0050] The proportional coefficient (Kp) of the proportional-integral (PI) algorithm can be set to 0.8, 1.0, or 1.2, and the integral time (Ti) can be set to 0.5 s, 1.0 s, or 1.5 s. The algorithm calculates the correction amount based on the real-time pressure difference (ΔP) between the lower and upper spring groups. For example, when ΔP = 10 N, the output pressure adjustment amount is Kp×ΔP + (1 / Ti)∫ΔP dt. The corrected pressure gradient change rate is limited to ±5 N / s, ±8 N / s, or ±10 N / s to ensure a smooth two-stage transition.

[0051] The PI parameters are optimized through a step response test. A step pressure signal (such as a sudden increase from 0 N to 30 N) is applied to the system, and the pressure overshoot and settling time are recorded. Kp and Ti are adjusted to make the overshoot ≤5% and the settling time ≤0.3 s. The control algorithm is implemented in the PLC through ladder diagram or structured text programming, and the operation cycle is synchronized with the sensor sampling cycle.

[0052] The multi-point layout and high-frequency sampling of the pressure sensors in this embodiment ensure the real-time and accuracy of the clamping force distribution data; the dynamic compensation mechanism effectively suppresses local pressure imbalance, reducing the seal failure rate; the proportional-integral algorithm controls the pressure gradient fluctuation within ±5 N / s, significantly improving the smoothness of the clamping process and reducing the deformation of the bag mouth.

[0053] Furthermore, in another embodiment, at the initial stage of the closing of the clamping plate 6, the PLC controller controls the bi-directional cylinder drive mechanism 2 to increase the output pressure at a first pressure slope, and the slope can be selected from 0.5 MPa / s, 0.8 MPa / s, or 1.0 MPa / s. The pre-pressure threshold is set according to the material of the packaging bag 7. For example, it is set to 30 N for PE bags and 50 N for aluminum foil bags. When the pressure sensor 607 detects that the pressure of the lower spring group 6011 reaches the threshold, the PLC switches to the second pressure slope, and the slope can be selected from 0.3 MPa / s, 0.4 MPa / s, or 0.5 MPa / s. At the same time, the auxiliary sealing action of the upper spring group 6012 is started. The switching trigger signal is transmitted through a high-speed counter (response time ≤5 ms) to ensure that the stage switching delay ≤20 ms.

[0054] The opening of the proportional valve of the cylinder drive mechanism 2 can be set to 70%, 80%, or 90% in the first stage and adjusted to 40%, 50%, or 60% in the second stage. For example, the first slope of 0.8 MPa / s corresponds to an opening of 80%, and the second slope of 0.4 MPa / s corresponds to an opening of 50%. The pressure sensor (607) collects data every 20 ms, and noise interference is eliminated through the moving average filtering (window size of 5 samplings) of the PLC.

[0055] The proportional-integral algorithm dynamically adjusts the second pressure slope according to the real-time pressure difference (ΔP) between the lower and upper spring groups. The ΔP threshold can be set to 5N, 8N, or 10N. For example, when ΔP = 8N, the slope correction amount output by the algorithm is -10%, -15%, or -20% of the current slope. The proportional coefficient (Kp) can be selected as 0.5, 0.7, or 1.0, and the integral time (Ti) can be selected as 1.0s, 1.5s, or 2.0s. The corrected pressure gradient change rate is limited to ±5N / s, ±8N / s, or ±10N / s.

[0056] The adjustment process is optimized through a step response test. A pressure step signal (such as a sudden increase from 20N to 40N) is applied to the system, and the overshoot and settling time are recorded. Kp and Ti are adjusted to make the overshoot ≤ 5% and the settling time ≤ 0.5s. The correction instruction is executed in real time through the PID function block of the PLC, and the operation cycle is synchronized with the sensor sampling cycle.

[0057] At the end of the clamping stage, the output pressure of the cylinder enters the pressure-holding stage, maintaining the pressure ratio between the lower and upper parts at 2:1, 3:1, or 4:1 (such as 40N in the lower part and 10N in the upper part). The pressure-holding duration can be set to 2s, 3s, or 5s, and the pressure fluctuation range during this period is limited to ±3%, ±5%, or ±8%. The sealing detection unit (such as a negative pressure generator) is started after the pressure-holding ends, injecting a negative pressure of -5kPa, -8kPa, or -10kPa into the packaging bag 7, and detecting the pressure recovery rate. If the recovery per unit time exceeds 0.5kPa / s, 0.8kPa / s, or 1.0kPa / s, it is determined that the seal is unqualified and an alarm is triggered.

[0058] The pressure maintenance during the pressure-holding stage is achieved by finely adjusting the opening of the proportional valve, and the adjustment range is ±2%, ±3%, or ±5%. For example, when the pressure drops by 3%, the opening of the proportional valve increases by 3%. The detected data is recorded by the PLC and associated with the production batch, and abnormal data automatically generates a maintenance log.

[0059] The staged pressure slope control of this embodiment realizes the smooth loading of the clamping force, reduces the risk of bag mouth deformation; the dynamic gradient adjustment mechanism effectively suppresses pressure mutations and improves the sealing uniformity; the closed-loop verification during the pressure-holding stage ensures the sealing reliability and significantly reduces the false soldering rate.

[0060] Further, in another embodiment, displacement sensors 9 are symmetrically installed between the clamping plates 6. The displacement sensors can be LVDT linear displacement sensors or photoelectric encoders. The detection ends point in the closing direction of the clamping plates 6, and the installation positions are 20 mm, 30 mm, or 40 mm from the bottom of the enclosure plate 603. The measuring ranges of the displacement sensors 9 can be selected as 0 - 100 mm, 0 - 150 mm, or 0 - 200 mm, the detection accuracy is ±0.1 mm, ±0.2 mm, or ±0.3 mm, and the sampling frequency is set to 100 Hz, 200 Hz, or 500 Hz. The signals of the sensors 9 are connected to the high-speed counter module of the PLC controller through shielded cables. The counter resolution can be selected as 16 bits or 24 bits, and the signal transmission delay ≤ 5 ms.

[0061] The mounting brackets of the displacement sensors 9 can be made of aluminum alloy and are fixed to the side walls of the clamping plates 6 by M6 bolts. The distance between the detection surface of the displacement sensor 9 and the reflector (or target) of the opposite clamping plate 6 is set to 5 mm, 8 mm, or 10 mm to ensure signal stability. For example, when the distance between the clamping plates 6 is 80 mm, the initial installation distance is set to 10 mm, and the relative displacement change is detected in real time during the closing process.

[0062] When the displacement sensor 9 detects that the moving distance of the clamping plate 6 reaches 3 / 8 of the height of the enclosure plate 603 (for example, when the height of the enclosure plate 603 is 80 mm, the trigger position is 30 mm), the PLC controller generates a trigger signal. The trigger signal is transmitted to the cylinder control valve (such as a proportional valve or a servo valve) through the digital quantity output module, and the valve opening is adjusted from the initial values of 50%, 60%, or 70% to 30%, 40%, or 50%. The valve opening adjustment curve is a linear increasing function, and the slope is inversely proportional to the pressure gradient change rate of the lower spring group 6011. For example, if the lower pressure gradient is 15 N / s, the slope of the valve opening curve is -0.5% / (N / s), that is, for every increase of 1 N / s in the pressure gradient, the valve opening decreases by 0.5%.

[0063] The response time of the cylinder control valve ≤ 10 ms, and the valve opening adjustment error is controlled within ±2%. The PLC controller calibrates the valve opening value in real time through the PID algorithm. For example, when it is detected that the actual valve opening deviates from the target value by 3%, a compensation current (4 - 20 mA) is output to adjust the spool position. The trigger signal and the data of the pressure sensor 607 are synchronously verified. If the deviation between the two exceeds 5%, an abnormal alarm is triggered.

[0064] During the auxiliary sealing stage, the PLC controller monitors the moving speed of the clamping plate 6 in real time through the displacement sensor 9, and combines the pressure difference (ΔP) between the upper and lower parts fed back by the pressure sensor 607 to dynamically correct the opening of the cylinder control valve. The ΔP threshold is set to 5N, 8N or 10N. For example, when ΔP = 8N, the opening correction amount is -5%, -8% or -10% of the current value. The slope of the corrected opening curve is limited to ±0.3% / (N / s), ±0.5% / (N / s) or ±0.8% / (N / s) to prevent pressure oscillation.

[0065] The cooperative control parameters are calibrated through experiments. During the closing process of the clamping plate 6, the load is gradually increased and the displacement-pressure relationship curve is recorded to optimize the opening correction coefficient. For example, when the moving speed of the clamping plate 6 decreases from 10mm / s to 5mm / s, the opening adjustment amount increases from -5% to -10% to maintain the stability of the pressure gradient. The control logic is implemented by function block programming in the PLC, and the operation cycle is synchronized with the sensor sampling cycle (10ms).

[0066] Further, in another implementation, after the trigger signal is generated, the PLC controller real-time collects the moving distance data of the displacement sensor 9 through the high-speed counter module, and the sampling period can be set to 10ms, 20ms or 30ms. The pressure gradient change rate during the preloading stage of the lower spring group 6011 is calculated through the data of the pressure sensor 607, and the calculation formula is ΔP / Δt, where ΔP is the pressure difference between adjacent sampling points and Δt is the sampling period. The pressure gradient change rate range can be set to 5N / s, 10N / s or 15N / s, and an abnormal flag is triggered when it exceeds the range.

[0067] The high-speed counter module can select a 24-bit resolution and a counting frequency ≥1MHz to ensure the displacement data accuracy of ±0.1mm. The data of the pressure sensor 607 is collected through the analog input module of the PLC, and the module conversion accuracy ≤0.1%. The data calculation period is synchronized with the sampling period, for example, the gradient value is updated every 20ms.

[0068] According to the pressure gradient change rate, the opening adjustment curve of the cylinder control valve is dynamically set. The curve is a linearly increasing function, and the slope can be selected as -0.3% / (N / s), -0.5% / (N / s) or -0.8% / (N / s). For example, if the lower pressure gradient is 10N / s and the slope is set to -0.5% / (N / s), the opening decreases by 5% per second. The initial opening can be set to 50%, 60% or 70%, and the target opening is set to 30%, 40% or 50% according to the sealing stage requirements.

[0069] The proportional valve can be an electro-pneumatic proportional valve. The input signal is 4 - 20mA, and the opening linearity error ≤ ±1.5%. The adjustment curve parameters are written through the PID function block of the PLC, and the target opening value is updated every 10ms. For example, when the pressure gradient drops from 12N / s to 8N / s, the slope is adjusted from - 0.6% / (N / s) to - 0.4% / (N / s), and the opening adjustment rate slows down accordingly.

[0070] In the auxiliary sealing stage, the PLC controller monitors the pressure rising curve of the upper spring group 6012 in real time through the pressure sensor 607. The fluctuation amplitude threshold can be set to ±5N, ±8N or ±10N. When the detected fluctuation exceeds the limit, the proportional integral algorithm calculates the reverse compensation amount. The compensation amount formula is Kp×ΔP + Ki×∫ΔP dt, where Kp can be selected as 0.5, 0.7 or 1.0, and Ki can be selected as 0.1, 0.2 or 0.3. The corrected opening adjustment curve is adjusted by superimposing the compensation amount. For example, when ΔP = +8N, the opening is reduced by 3%.

[0071] The correction parameters are optimized through the step response test. Apply a disturbance pressure of ±10N to the system, record the recovery time and overshoot, and adjust Kp and Ki to make the recovery time ≤ 0.5s and the overshoot ≤ 3%. The compensation instruction execution cycle is the same as the sensor sampling cycle (such as 20ms) to ensure real-time performance. For example, when the pressure fluctuates by +8N, the opening drops from 45% to 42%, and the pressure recovers to the set value within 0.4s.

[0072] Furthermore, in another embodiment, the gas flow sensors 10 are symmetrically installed outside the top plate 602 of the splint 6, with the detection ends facing the exhaust passage of the packaging bag 7. The installation spacing can be selected as 100mm, 120mm or 150mm. The range of the gas flow sensors 10 can be selected as 0 - 10L / min, 0 - 20L / min or 0 - 30L / min, the detection accuracy is ±1%FS, and the sampling frequency is set to 10Hz, 20Hz or 30Hz. The housing of the gas flow sensors 10 can be made of 316 stainless steel, with an IP65 protection level, and is fixed to the reserved hole position on the top plate 602 through M5 bolts, and the bolt pre-tightening torque is 2N・m to 3N・m. The signal is transmitted to the PLC controller through a shielded cable, and the cable length does not exceed 3m. The signal noise is suppressed by an RC filter circuit (cut-off frequency 5Hz).

[0073] The gas flow sensor 10 can be a thermal or differential pressure flowmeter, and the output signal is 4 - 20 mA or 0 - 10 V. During installation, the axis of the detection end is aligned with the center line of the exhaust passage, with a deviation ≤ ±2 mm. For example, for an exhaust passage with a width of 5 mm, the detection surface of the gas flow sensor 10 is 10 mm, 15 mm, or 20 mm away from the passage outlet, ensuring that the measurement error of the gas flow velocity ≤ ±3%.

[0074] The database of the mapping relationship between the air permeability coefficient and the material density pre - stored in the PLC controller contains air permeability data of materials such as PE, PP, and aluminum foil. The air permeability coefficient is measured through standard tests (such as ASTM D737) and can range from 0.1 - 5.0 cm³ / (m²·s·Pa). When the packaging bag 7 enters the clamping station, the operator inputs the material type (such as "PE - 30") and the material density (such as 0.8 g / cm³) through the human - machine interface. The PLC calls the database to match the air permeability coefficient (such as 2.5 cm³ / (m²·s·Pa)). The initial flow threshold is calculated by linear interpolation, and the formula is: Threshold = Base value × (Air permeability coefficient / Reference coefficient)+Density compensation term. The base value can be 5 L / min, 8 L / min, or 10 L / min, and the density compensation term can be - 1 L / min, 0 L / min, or + 1 L / min.

[0075] During real - time correction, the PLC adjusts the threshold every 10 s, 20 s, or 30 s according to the average value of the recent 30 flow sampling data. The correction amount can be set to ±5%, ±8%, or ±10% of the initial value. For example, if the initial threshold is 8 L / min and the average flow rate detected continuously for 3 times is 7.5 L / min, then the threshold is lowered to 7.6 L / min (correction amount - 5%). The corrected threshold is output to the comparator through the DAC module, and the trigger condition judgment delay ≤ 10 ms.

[0076] When the flow rate per unit time drops to the dynamic threshold (such as 7 L / min), the PLC controller increases the output pressure of the two - way cylinder drive mechanism 2 on the lower spring group 6011 through the proportional valve. The increase amplitude can be 10%, 15%, or 20% of the current pressure. For example, when the current pressure is 40 N, it is increased to 44 N, 46 N, or 48 N. At the same time, the pressure - holding time is extended to 1.2 times, 1.3 times, or 1.5 times the initial set value (such as 3 s), that is, extended to 3.6 s, 3.9 s, or 4.5 s.

[0077] During the holding and extension period, the PLC continuously monitors the flow rate change. If the flow rate rebounds to 105%, 108% or 110% of the threshold value (for example, rebounds to 7.35L / min, 7.56L / min or 7.7L / min under the threshold value of 7L / min), the clamping is immediately terminated and the airtightness detection is started. If the flow rate is detected to be lower than the threshold value (such as 6.5L / min) for 3 consecutive times, it is determined that the packaging bag 7 is damaged or the clamping fails, and an alarm signal (audible and visual alarm) is triggered. The cylinder driving mechanism 2 retracts to the initial position, and the retraction speed is set to 50%, 60% or 70% of the nominal value.

[0078] The precise monitoring and dynamic threshold adjustment of the gas flow rate sensor 10 in this embodiment are adapted to different materials of the packaging bag 7, reducing the false soldering of the seal caused by gas residue; the coordinated control of pressurization and extension ensures the thoroughness of exhaust, and at the same time avoids excessive compression from damaging the bag mouth; the abnormal flow rate continuous detection mechanism quickly identifies bag breakage or clamping failure, improving the system safety and production efficiency.

[0079] Furthermore, in another embodiment, the air permeability coefficient database pre-stored in the PLC controller is established by experimentally measuring the air permeability rate of different materials of the packaging bag 7, covering PE, PP, nylon and aluminum foil composite materials. For example, the air permeability coefficient range of the PE material is 0.5 - 2.0 cm³ / (m²·s·Pa), and that of the aluminum foil composite material is 0.1 - 0.5 cm³ / (m²·s·Pa). The test conditions refer to the ISO 5631 standard (temperature 23°C, humidity 50%). The material density data is measured by the weighing method, and the range is set to 0.5 - 1.5 g / cm³, and is classified and stored at intervals of 0.1 g / cm³. The operator can input the material code (such as "AL-05") and density value (such as 0.8 g / cm³) of the current batch of packaging bags 7 through the human-machine interface or the QR code scanner, and the PLC calls the database to match the corresponding air permeability coefficient.

[0080] The database is stored in the EEPROM of the PLC or an external SD card, and the capacity supports at least 1000 groups of data. The QR code scanner can select an industrial-grade barcode reader, with a decoding speed ≤ 50 ms and an error rate ≤ 0.01%. When inputting data, if the material code fails to match successfully, the PLC prompts to manually select a similar material (such as matching "AL-05" to "AL-04" or "AL-06").

[0081] The initial gas flow threshold is calculated by a linear interpolation formula: Threshold = Base value + (Permeability coefficient - Reference coefficient) × Slope coefficient + Density compensation term. For example, the reference coefficient is set to 1.0 cm³ / (m²·s·Pa), the base value is 8 L / min, the slope coefficient is 2 L / (min·cm³ / (m²·s·Pa)), and the density compensation term is -0.5 L / min (density ≥ 1.0 g / cm³) or +0.5 L / min (density < 1.0 g / cm³). If the permeability coefficient is 0.8 cm³ / (m²·s·Pa) and the density is 0.8 g / cm³, then the threshold = 8 + (0.8 - 1.0) × 2 + 0.5 = 7.1 L / min.

[0082] The interpolation parameters are optimized through calibration experiments. Ten sets of typical material and density combinations are selected, the exhaust flow is measured, and the formula coefficients are fitted to ensure that the calculation error ≤ ±5%. The interpolation result is calculated in real time by the floating-point operation unit of the PLC, and the operation cycle ≤ 10 ms.

[0083] During the clamping process, the PLC collects the most recent 30 flow data every 10 s, 20 s, or 30 s, and calculates the mean value and standard deviation. If the mean value deviates from the current threshold by ±5%, ±8%, or ±10%, the threshold is corrected according to the deviation ratio. For example, when the mean value is 8% lower than the threshold, the threshold is lowered by 8%. The corrected threshold range is limited to 80% - 120% of the initial value to avoid over-adjustment.

[0084] If the flow rate is detected to be lower than 90% of the corrected threshold for three consecutive times (e.g., when the threshold is 7 L / min, the detected value ≤ 6.3 L / min), it is determined that the packaging bag 7 is damaged or the clamping fails. The PLC triggers an audible and visual alarm (the alarm volume ≥ 80 dB), and controls the cylinder drive mechanism 2 to retract to the initial position at 50%, 60%, or 70% of the nominal speed. During the retraction process, the pressure sensor 607 monitors the release of the clamping force and stops when the pressure drops to a safe value (≤ 5 N).

[0085] Further, in another embodiment, the thickness gauge 11 is symmetrically installed outside the top plate 602 of the clamping plate 6. The optical path of the transmitting end and the receiving end is perpendicular to the clamping surface, and the installation height is 50mm, 80mm or 100mm from the clamping surface. The measuring range of the thickness gauge 11 can be selected as 0.1 - 3mm, 0.1 - 5mm or 0.1 - 10mm, the detection accuracy is ±0.01mm, ±0.02mm or ±0.05mm, and the sampling frequency is set to 50Hz, 100Hz or 200Hz. The sensor housing can be made of 316 stainless steel with an IP67 protection level and is fixed to the reserved bracket on the top plate 602 by M4 bolts, and the pre-tightening torque of the bolts is 1.5N·m to 2.5N·m. The signal is transmitted to the PLC controller through a shielded cable, and the cable length does not exceed 2m. The signal noise is suppressed by digital filtering (moving average window size 5 - 10 samples).

[0086] The thickness gauge 11 can be a laser triangulation reflection type or a laser interferometric sensor, and the output signal is 4 - 20mA or RS485 digital signal. During installation, the center line of the optical path is aligned with the center of the clamping surface, and the deviation ≤ ±1mm. For example, for the detection of the thickness of the bag mouth, the diameter of the focused spot of the thickness gauge 11 ≤ 0.5mm to ensure the accuracy of measuring the local thickness.

[0087] The PLC controller dynamically generates a cylinder speed regulation command according to the real-time detected thickness of the bag mouth. The preset nominal thickness is matched with the material type of the packaging bag 7 by the look-up table method. For example, the nominal thickness of the PE material is 0.1mm, the aluminum foil material is 0.2mm, and the composite film material is 0.3mm. When the measured thickness is less than 90% of the nominal value (such as 0.18mm is detected when the nominal value is 0.2mm), the PLC controls the closing speed of the cylinder to drop to 70%, 75% or 80% of the nominal speed, and at the same time raises the pre-pressure to 120%, 125% or 130% of the nominal value. When the measured thickness is greater than 110% of the nominal value (such as 0.22mm is detected when the nominal value is 0.2mm), the cylinder speed is increased to 120%, 130% or 150% of the nominal value, and the pre-pressure is reduced to 80%, 85% or 90% of the nominal value.

[0088] The speed adjustment is linearly controlled by the opening of the proportional valve. For example, the nominal speed of 100mm / s corresponds to an opening of 60%. When the speed is adjusted to 80%, the opening is set to 48%. The speed change rate is limited to 5%, 8% or 10% per second to avoid the vibration of the clamping plate 6 caused by the sudden change of acceleration. The pressure adjustment is realized through the pressure gain module of the proportional valve. For example, when the nominal value of the pre-pressure is 40N and it is increased to 120% (i.e., 48N), the output air pressure of the proportional valve increases from 0.5MPa to 0.6MPa.

[0089] The laser thickness gauge 11 updates the thickness data of the bag mouth every 2 s, 3 s or 5 s. The PLC calculates the thickness mean value through a sliding window (the most recent 5 - 10 samplings) to eliminate the interference of instantaneous fluctuations. The preset nominal value database is stored in the PLC memory and supports editing through the human - machine interface or importing a CSV file. For example, when the operator inputs the material code "PE - 02", the PLC calls the corresponding nominal thickness of 0.2 mm and the speed - pressure parameter group.

[0090] During the closed - loop control process, the PLC checks the matching of the thickness data and the regulation instruction every 10 ms. If a sudden change in thickness is detected (such as a sudden increase from 0.2 mm to 0.3 mm), the speed and pressure adjustments are immediately triggered, and the response delay ≤ 20 ms. After the adjustment is completed, the deviation between the actual pressure and the target value is verified through the pressure sensor (607). If it exceeds ±5 N, the opening of the proportional valve is recalibrated.

[0091] As Figure 4 shown, an example of the bag - clamping method of a bag - clamping system of the present invention includes: A pair of clamping plates are symmetrically arranged on both sides of the packaging bag conveying path. The U - shaped frame of the clamping plate is composed of a top plate and a surrounding plate (603). The thickness of the rectangular flange can be selected as 6 mm, 8 mm or 10 mm, and the width can be selected as 15 mm, 20 mm or 25 mm. The horizontal substrate of the support frame assembly is welded to the side plate and the inclined reinforcing plate to form a triangular support structure, and the inclined angle can be selected as 30 degrees, 45 degrees or 60 degrees. After the flange is inserted into the positioning groove, it is fixed by M10 bolts, and the bolt pre - tightening torque can be selected as 15 N·m, 20 N·m or 25 N·m. During assembly, the support frame assembly is connected to the support arm through a connecting plate, and the support arm is rigidly fixed to the telescopic end of the double - acting cylinder driving mechanism through a flange.

[0092] The stroke range of the double-acting cylinder drive mechanism can be selected as 100mm, 150mm or 200mm, and the output thrust can be selected as 500N, 600N or 800N. During the closing process of the clamping plate, the lower spring group is composed of helical compression springs with wire diameters of 1.2mm, 1.5mm or 1.8mm, the distance between adjacent springs is 4mm, 5mm or 6mm, and the free height is 3 / 8 of the height of the enclosure (for example, when the enclosure height is 80mm, the free height is 30mm). The cylinder increases the output pressure at the first pressure slope (0.5MPa / s, 0.8MPa / s or 1.0MPa / s) to compress the lower spring group to the pre-pressure threshold (30N, 40N or 50N). When the pressure sensor (607) detects the threshold, it switches to the second pressure slope (0.3MPa / s, 0.4MPa / s or 0.5MPa / s). The upper spring group (6012) is composed of springs with wire diameters of 0.8mm, 1.0mm or 1.2mm, the distance is 8mm, 9mm or 10mm, and the free height is 5 / 8 of the height of the enclosure (for example, when the enclosure height is 80mm, the free height is 50mm).

[0093] The displacement sensors are symmetrically installed on the side walls of the clamping plate, with the detection ends pointing in the closing direction. The measurement range can be selected as 0 - 100mm, 0 - 150mm or 0 - 200mm, and the accuracy is ±0.1mm. When it is detected that the moving distance of the clamping plate reaches 3 / 8 of the height of the enclosure (for example, the trigger position is 30mm when the enclosure height is 80mm), the PLC generates a trigger signal to control the cylinder to switch to the auxiliary sealing stage. The trigger signal is transmitted through a high-speed counter (response time ≤ 5ms), and the opening degree of the cylinder control valve is adjusted from 60%, 70% or 80% to 40%, 50% or 60%. The proportional-integral algorithm dynamically adjusts the second pressure slope according to the pressure difference between the lower and upper spring groups (ΔP = 5N, 8N or 10N), and the gradient change rate is limited to ±5N / s, ±8N / s or ±10N / s.

[0094] The gas flow sensor is installed outside the top plate, with the detection end facing the exhaust passage. The measurement range can be selected as 0 - 10L / min, 0 - 20L / min or 0 - 30L / min. When the flow rate per unit time drops to the dynamic threshold (such as 7L / min, 8L / min or 9L / min), the PLC controls the proportional valve to increase the pressure of the lower spring group by 10%, 15% or 20%, and extends the pressure holding time to 1.2 times, 1.3 times or 1.5 times of the initial setting (such as 3s). If the flow rate rises to 105%, 108% or 110% of the threshold (such as 7.35L / min, 7.56L / min or 7.7L / min), immediately terminate the clamping and start the sealing detection.

[0095] The laser thickness gauge is installed on the outside of the top plate, and the optical path is perpendicular to the clamping surface. The measuring range is 0.1 - 3 mm, 0.1 - 5 mm or 0.1 - 10 mm, and the accuracy is ±0.02 mm. When the detected thickness is less than the nominal value (e.g., 0.18 mm vs. nominal 0.2 mm), the cylinder speed drops to 70%, 75% or 80% of the nominal speed (e.g., 100 mm / s), and the pre-pressure is increased to 120%, 125% or 130% of the nominal value (e.g., 40 N). When the thickness is greater than the nominal value (e.g., 0.22 mm), the speed is increased to 120%, 130% or 150%, and the pre-pressure is reduced to 80%, 85% or 90%. The speed change rate is limited to 5%, 8% or 10% per second, and the thickness measurement data is updated every 2 seconds, 3 seconds or 5 seconds.

[0096] After the pressure holding ends, the sealing detection unit injects a negative pressure of -5 kPa, -8 kPa or -10 kPa through a vacuum pump. The gas flow sensor monitors the pressure recovery rate, and the threshold is set to 0.5 kPa / s, 0.8 kPa / s or 1.0 kPa / s. If the detection fails continuously for 3 times, the PLC determines that the component is abnormal and triggers a maintenance reminder. The alarm signal displays the fault code (such as "E01 spring failure") through the human-machine interface, and the cylinder retracts to the initial position. The retraction speed is set to 50%, 60% or 70% of the nominal value. The maintenance log is stored in the PLC memory and supports USB export.

[0097] Staged clamping and dynamic regulation ensure the prevention of damage to thin-walled bags and sufficient sealing of thick-walled bags; multi-sensor collaboration improves the matching accuracy of clamping parameters and the bag mouth state; the closed-loop detection and abnormal handling mechanism reduces manual intervention and ensures the stable operation of the system. Embodiment

[0098] This embodiment is for the automated packaging scenario of white sugar granules (density 1.0 g / cm³), and a PE material packaging bag with a thickness of 0.2 mm is selected. The bag clamping system is configured as follows: Clamping plate and supporting frame assembly: The thickness of the rectangular flange of the clamping plate is 8 mm, the width is 20 mm, the included angle of the inclined reinforcing plate of the supporting frame is 45°, the depth of the positioning groove is 8 mm, and it is fixed by M10 bolts (pre-tightening torque 20 N·m).

[0099] Spring assembly: The lower spring group uses 65Mn springs with a wire diameter of 1.5 mm and a spacing of 5 mm, and the free height is 30 mm (the height of the surrounding plate is 80 mm); the upper spring group uses SUS304 springs with a wire diameter of 1.0 mm and a spacing of 9 mm, and the free height is 50 mm.

[0100] The sensor configuration includes: displacement sensor: measuring range 0 - 150 mm, accuracy ±0.1 mm, installation spacing 30 mm; pressure sensor: measuring range 0 - 50 N, sampling frequency 200 Hz; gas flow sensor: measuring range 0 - 20 L / min, detection end 15 mm away from the exhaust passage; laser thickness gauge: measuring range 0.1 - 3 mm, accuracy ±0.02 mm, spot diameter 0.3 mm.

[0101] The clamping process and dynamic control include: Step 1: Clamping plate positioning and initial clamping The packaging bag enters the clamping station through the conveying platform, and the laser thickness gauge detects that the thickness of the bag mouth is 0.18 mm (nominal 0.2 mm). The PLC controls the cylinder driving mechanism to reduce the closing speed to 75% (75 mm / s) of the nominal speed (100 mm / s), and the pre-pressure is increased to 125% (50 N) of the nominal value (40 N).

[0102] Step 2: Applying clamping force in stages Pre-pressure stage: The cylinder pressurizes at a slope of 0.8 MPa / s, and the lower spring group is compressed to the pre-pressure threshold of 40 N to stabilize the white sugar granule area; Auxiliary sealing stage: Triggered when the displacement sensor detects that the clamping plate moves to the 30 - mm position, the cylinder switches to a slope of 0.4 MPa / s, the elastic pressing piece contacts the upper part of the bag mouth, provides a pre-pressure of 4 N and lifts it by 3 mm to eliminate wrinkles, and the exhaust passage (width 4 mm) discharges the air in the bag; Pressure - holding stage: The upper spring group is compressed to 65% of its free height, maintaining the upper - lower pressure ratio of 3:1 (lower 45 N: upper 15 N), and the pressure - holding time is 3.5 s (1.2 times the initial 3 s).

[0103] Step 3: Exhaust and airtightness detection The gas flow sensor monitors that the flow rate drops to the dynamic threshold of 7 L / min (air permeability coefficient 1.5 cm³ / (m²·s·Pa)), the PLC controls the proportional valve to increase the pressure to 55 N (+10%), and extends the pressure - holding time to 4.2 s. When the flow rate rises back to 7.4 L / min (105% of the threshold), the clamping is terminated. The airtightness detection unit injects a negative pressure of - 8 kPa, and if the pressure rise rate within 5 s is ≤0.8 kPa / s, the seal is determined to be qualified.

[0104] 3. Abnormal handling and maintenance If the flow rate is detected to be lower than 6.3 L / min (90% of the threshold) continuously for 3 times, the PLC triggers an alarm and retracts the cylinder to the initial position (speed 50 mm / s). The maintenance log records "E02 - abnormal flow rate", indicating to check the spring group or the alignment of the bag mouth.

[0105] The sealing qualification rate of this embodiment has been increased from 85% of the traditional system to 98%, and there is no leakage of white granulated sugar; the breakage rate of thin bags (0.18 mm) has been reduced from 8% to 0.5%; the automatic adaptation of thickness deviation is ±0.05 mm, and it is suitable for various materials such as PE and composite films; the single clamping cycle is shortened to 6 s, which is 15% higher than the traditional system. It can be seen that this embodiment effectively solves the problems of dust interference, easy damage of thin bags and poor sealing in the packaging of white granulated sugar through the cooperation of multi-sensors and phased clamping control, and significantly improves the automation packaging efficiency and quality.

[0106] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the field, additional modifications can be easily achieved.

Claims

1. A bag clamping system, characterized in that, Comprising: A pair of clamping plates symmetrically arranged on both sides of the packaging bag conveying path. Each clamping plate includes a U-shaped frame body with an open lower end. The frame body is composed of a top plate and side plates extending downward on both sides. Rectangular flanges are provided on the outer sides of the top plate and the side plates; A supporting frame assembly, including a horizontal base plate, side plates vertically welded to both sides of the base plate, and inclined reinforcing plates connecting the side plates and the base plate. The included angle between the inclined reinforcing plates and the base plate and the side plates is 30 degrees to 60 degrees. Rectangular positioning grooves matching the flanges of the clamping plates are provided on the inner sides of the side plates. After the flanges are inserted into the positioning grooves, they are fixed by bolts; A double-acting cylinder driving mechanism, whose cylinder body is fixed to the frame. The telescopic end of the double-acting cylinder driving mechanism is rigidly connected to the base plate of the supporting frame assembly through a support arm and a connecting plate; A spring assembly, including a lower spring group and an upper spring group installed on the inner sides of the side plates of the clamping plates. The lower spring group is composed of helical compression springs with a wire diameter of 1.2 mm to 1.8 mm, and the distance between adjacent springs is 4 mm to 6 mm. The upper spring group is composed of helical compression springs with a wire diameter of 0.8 mm to 1.2 mm, and the distance between adjacent springs is 8 mm to 10 mm. The free height of the lower spring group is 3 / 8 of the height of the side plate, and the free height of the upper spring group is 5 / 8 of the height of the side plate; A sunk groove is provided at the top of the horizontal base plate of the supporting frame assembly. The length of the sunk groove is the same as the length of the flange of the top plate of the clamping plate, and the bottom surface of the sunk groove contacts the lower surface of the flange of the top plate; An inclined reinforcing rod is welded between the connecting plate and the side plate of the supporting frame assembly. One end of the inclined reinforcing rod is welded at the lower side surface of the connecting plate, and the other end is welded at the lower part of the side plate of the supporting frame assembly.

2. The bag clamping system according to claim 1, characterized in that, A plurality of elastic pressing pieces are arranged on the upper part of the top plate of the clamping plate. The elastic pressing pieces extend obliquely inward and upward of the clamping plate, and the ends are bent into arc-shaped contact surfaces; The elastic pressing pieces are arranged along the length direction of the top plate, and the positions of the elastic pressing pieces on the left and right clamping plates correspond to form clamping and limiting of the packaging bag; During the closing process of the clamping plates, the lower spring group first contacts and compresses the bag mouth material area; when the clamping plates continue to move, the arc-shaped contact surface of the elastic pressing piece contacts the upper part of the bag mouth, provides a pre-pressure through elastic deformation, and synchronously lifts the bag mouth to eliminate sag deformation; finally, the upper spring group presses the upper part of the bag mouth to complete the sealing through the spring compression force, and the gap between adjacent elastic pressing pieces forms an exhaust channel.

3. The bag clamping system according to claim 1, characterized in that, A pressure sensor is provided on the inner side of the side plate of the clamping plate. The pressure sensor monitors the clamping force data of the lower spring group and the upper spring group in real time during the clamping process and feeds the data back to the PLC controller; the PLC controller has a preset clamping force distribution curve, and the clamping force distribution curve is set according to the material distribution characteristics and sealing requirements of the packaging bag; During the closing process of the clamping plates, the PLC controller compares the deviation between the real-time clamping force data and the preset curve, and dynamically compensates for the local imbalance of the clamping force by adjusting the output pressure of the double-acting cylinder driving mechanism; the clamping force distribution curve includes a pre-pressing stage of the lower spring group and an auxiliary sealing stage of the upper spring group, and the pressure gradient between the two stages is smoothly transitioned through the proportional integral algorithm of the PLC controller.

4. The bag clamping system according to claim 3, characterized in that, The smooth transition between the pre-pressing stage and the auxiliary sealing stage of the clamping force distribution curve is achieved through the following steps: At the initial stage of the clamping plate closing, the PLC controller controls the double-acting cylinder driving mechanism to increase the output pressure at the first pressure slope, so that the lower spring group is compressed to a preset preloading threshold value, and the preloading threshold value corresponds to the initial sealing pressure of the packaging bag material area; When the pressure sensor detects that the pressure of the lower spring group reaches the preloading threshold value, the PLC controller switches to the second pressure slope and increases the output pressure at a rate lower than the first pressure slope, and synchronously starts the auxiliary sealing action of the upper spring group; The proportional-integral algorithm dynamically adjusts the second pressure slope according to the real-time pressure difference between the lower spring group and the upper spring group, ensuring that the pressure gradient change rate in the two stages does not exceed the preset fluctuation tolerance; At the end of the clamping action, the PLC controller controls the cylinder output pressure to enter the pressure-holding stage, maintaining the preset upper and lower pressure ratios in the clamping force distribution curve until the sealing detection unit completes the sealing verification.

5. The bag clamping system according to claim 4, characterized in that, Displacement sensors are symmetrically arranged between the clamping plates, and the detection ends of the displacement sensors point to the clamping plate closing direction; at the initial stage of the clamping plate closing, the displacement sensors detect the relative moving distance between the two clamping plates in real time, and transmit the detection data to the PLC controller through a high-speed counter; When the moving distance reaches 3 / 8 of the height of the clamping plate apron, the PLC controller generates a trigger signal, controls the double-acting cylinder driving mechanism to switch to the auxiliary sealing stage, and starts the loading action of the upper spring group; the trigger signal synchronously adjusts the opening of the cylinder control valve to make the pressure loading rate of the upper spring group match the pressure gradient in the preloading stage of the lower spring group.

6. The bag clamping system according to claim 5, characterized in that After the trigger signal is generated, the PLC controller performs the following cooperative control actions: obtains the real-time moving distance data of the displacement sensor through the high-speed counter, and calculates the pressure gradient change rate in the preloading stage of the lower spring group; according to the pressure gradient change rate, dynamically sets the opening adjustment curve of the cylinder control valve, and the adjustment curve is a linearly increasing function, and its slope is inversely proportional to the pressure gradient change rate of the lower spring group; The cylinder control valve is a proportional valve, and its opening is adjusted synchronously according to the adjustment curve, so that the pressure loading rate of the upper spring group matches the pressure gradient in the preloading stage of the lower spring group; in the auxiliary sealing stage, the PLC controller monitors the pressure rising curve of the upper spring group in real time through the pressure sensor, and if it detects that the pressure fluctuation amplitude exceeds the preset threshold value, it corrects the opening adjustment curve of the cylinder control valve through the proportional-integral algorithm; the corrected opening adjustment curve suppresses the pressure oscillation by superimposing a reverse compensation amount.

7. The bag clamping system according to claim 6, characterized in that, Gas flow sensors are symmetrically installed on the outer sides of the top plates of the clamping plates, and the detection ends of the gas flow sensors face the exhaust passage of the packaging bag; During the clamping process, the gas flow sensors monitor the gas discharge flow rate in the bag in real time and feedback the flow rate data to the PLC controller; When it is detected that the gas flow rate per unit time drops to the preset threshold value, the PLC controller performs the following actions: Increase the output pressure of the double-acting cylinder driving mechanism on the lower spring group through the proportional valve, and the increase range is 10% to 20% of the current pressure; Synchronously extend the duration of the pressure-holding stage of the clamping action, and the extension amount is 1.2 times to 1.5 times of the initial set time; The gas flow threshold is dynamically set by the built-in algorithm of the PLC according to the air permeability coefficient of the packaging bag and the material density; during the extended holding pressure stage, the PLC controller continuously monitors the change of the gas flow. If the flow rate rebounds and exceeds the threshold, a clamping action termination instruction is triggered, and the airtightness detection process is entered.

8. The pocket system according to claim 7, characterized in that, The dynamic setting of the gas flow threshold is achieved through the following steps: A mapping relationship database of the air permeability coefficient of the packaging bag and the material density is pre-stored in the PLC controller. The air permeability coefficient is measured by experiments on the air permeability rate of different material packaging bags and classified and stored; when the packaging bag enters the clamping station, the material type and material density data of the current batch of packaging bags are input through the human-machine interface or the QR code scanner. The PLC controller calls the mapping relationship database to match the corresponding air permeability coefficient; based on the air permeability coefficient and the material density, the initial value of the gas flow threshold is calculated through a linear interpolation algorithm. The initial value increases with the increase of the air permeability coefficient and decreases with the increase of the material density; During the clamping process, the PLC controller dynamically corrects the threshold according to the real-time gas flow data. The correction amount is ±5% to ±10% of the initial value, and the correction frequency is once every 10 seconds to 30 seconds; during the extended holding pressure stage, if the gas flow rebounds to 105% to 110% of the corrected threshold, it is determined that the gas in the bag has been exhausted, and the PLC controller immediately terminates the clamping action and starts the airtightness detection process; If it is detected that the flow rate is still lower than the threshold after 3 consecutive rebounds, it is determined that the packaging bag is damaged or the clamping fails, and an alarm signal is triggered and the clamping plate is forced to retract to the initial position.

9. The bag clamping system according to claim 8, wherein Laser thickness gauges are symmetrically installed on the outer side of the top plate of the clamping plate. The optical path between the emitting end and the receiving end of the laser thickness gauge is perpendicular to the clamping surface, and is used to detect the thickness of the bag mouth of the packaging bag in real time; The detection data of the laser thickness gauge is transmitted to the PLC controller through a high-speed data bus. The PLC controller dynamically generates a cylinder speed regulation instruction according to the thickness of the bag mouth; when the thickness of the bag mouth is less than the preset nominal value, the PLC controller reduces the closing speed of the double-acting cylinder drive mechanism to 70% to 80% of the nominal speed to avoid clamping deformation caused by too fast speed of the thin-walled bag mouth; when the thickness of the bag mouth is greater than the preset nominal value, the PLC controller increases the cylinder closing speed to 120% to 150% of the nominal speed to compensate for the compressive hysteresis effect of the thick-walled bag mouth; The cylinder speed regulation instruction is linearly adjusted through the opening of the proportional valve, and the speed change rate is limited to 5% to 10% per second to prevent the clamping plate from vibrating caused by sudden acceleration; the preset nominal value is matched through the look-up table method of the PLC controller according to the material type of the packaging bag, and the laser thickness measurement data is updated every 2 seconds to 5 seconds during the clamping process.

10. A method for clamping a bag of the clamping bag system according to any one of claims 1 to 9, characterized in that, It includes the following steps: A pair of clamping plates are symmetrically arranged on both sides of the packaging bag conveying path. The U-shaped frame body of each clamping plate is inserted into the rectangular positioning groove of the supporting frame assembly through the rectangular flange of the top plate and the surrounding plate, and is fixed by bolts. The supporting frame assembly is formed by welding a horizontal base plate, a vertical side plate and an inclined reinforcing plate into a triangular support structure. The included angle between the inclined reinforcing plate and the base plate and the side plate is 30 degrees to 60 degrees; Drive the support arm and the connecting plate through a two-way cylinder drive mechanism, so that the supporting frame assembly drives the clamping plate to move towards the center to form a clamp; During the closing process of the clamping plate, use the lower spring group and the upper spring group installed on the inner side of the clamping plate fence to apply the clamping force in stages: The lower spring group is composed of spiral compression springs with a wire diameter of 1.2 mm to 1.8 mm, the distance between adjacent springs is 4 mm to 6 mm, and the free height is 3 / 8 of the height of the fence. At the initial stage of closing, increase the output pressure of the cylinder with the first pressure slope, so that the lower spring group is compressed to the preset preloading threshold; When the pressure sensor detects that the pressure of the lower spring group reaches the preloading threshold, switch to the second pressure slope, and increase the output pressure at a rate lower than the first pressure slope. Synchronously start the auxiliary sealing action of the upper spring group. The upper spring group is composed of spiral compression springs with a wire diameter of 0.8 mm to 1.2 mm, the distance between adjacent springs is 8 mm to 10 mm, and the free height is 5 / 8 of the height of the fence; Real-time detect the relative moving distance between the two clamping plates through a displacement sensor. When the moving distance reaches 3 / 8 of the height of the fence, trigger a signal to control the cylinder to switch to the auxiliary sealing stage, and dynamically adjust the second pressure slope through a proportional-integral algorithm to ensure that the pressure gradient change rate in the two stages does not exceed the preset fluctuation tolerance; At the end of clamping, enter the pressure holding stage and maintain the preset upper and lower pressure ratio. At the same time, monitor the gas discharge flow in the bag through a gas flow sensor: If the flow rate drops to the dynamically set threshold value per unit time, increase the pressure of the lower spring group by 10% to 20%, and extend the pressure holding time to 1.2 to 1.5 times of the initial setting; If the flow rate rebounds and exceeds the threshold value, terminate the clamping and start the airtightness detection; Real-time detect the thickness of the bag mouth through a laser thickness gauge, and dynamically adjust the closing speed and preloading pressure of the cylinder: When the thickness is less than the nominal value, reduce the cylinder speed to 70% to 80% of the nominal value, and increase the preloading pressure to 120% to 130%; When the thickness is greater than the nominal value, increase the cylinder speed to 120% to 150% of the nominal value, and reduce the preloading pressure to 80% to 90%; The control command is linearly adjusted through the opening of the proportional valve. The speed change rate is limited to 5% to 10% per second, and the thickness measurement data is updated every 2 to 5 seconds; After the airtightness detection is completed, if there are still defects after 3 consecutive calibrations, it is determined that the component is abnormal and a maintenance reminder is triggered.

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